1. Field of the Invention
The present invention relates to a glass fiber reinforced resin composition and a wheel cap formed of same.
2. Description of the Prior Art
Prior to now, resins have been used in making wheel caps for motor vehicles, such as automobiles, in order to satisfy the requirement for light weight. Since wheel caps must have good impact resistance, thermal resistance, etc., plastic materials such as nylon, modified polyphenylene oxide (PPO) and the like have been used in the resins. However, since these plastic materials are disadvantageously expensive, there is a need for a material which has good impact resistance, thermal resistance, etc., but is less expensive.
To meet this need, there has been proposed a wheel cap formed from a composition comprising a less expensive polypropylene resin and glass fiber, as set forth in Japanese Unexamined Utility Model Publication (KOKAI) No. 62333/1989.
It is generally known that glass fiber reinforced polypropylene is superior to nonreinforced polypropylene in its mechanical strength, rigidity, thermal resistance, creep resistance and the like. However, since the addition of glass fibers sometimes results in a poor appearance, various measures must be taken when preparing the glass fiber reinforced polypropylene in order to ensure that a good appearance is obtained.
For instance, in Japanese Examined Patent Publication (KOKOKU) No. 7618/1989, the desired characteristics are obtained in the produced glass fiber reinforced polypropylene resin primarily by requiring that only certain glass fibers in certain amounts be included in the resin. The composition disclosed by this publication requires the use of glass fibers having an average diameter of 7 .mu.m or less, added in a predetermined amount, to improve the appearance of the resulting product.